1. Field of the Invention
The present invention is generally related to a damping mechanism and, more particularly, to a mechanism which responds to changes in rotational speed of a propeller shaft and a propeller hub by temporarily decoupling, or partially decoupling, the propeller hub from the propeller shaft through relative axial movement of associated components.
2. Description of the Related Art
U.S. Pat. No. 4,223,773, which issued to Croisant et al. on Sep. 23, 1980, discloses a drive engaging apparatus. A clutch apparatus for a marine drive lower gear case includes a propeller shaft rotatably mounted in a gear case housing. A drive gear for both forward and reverse is positioned in the housing coaxial with the propeller shaft and a clutch member is rotatably fixed on the propeller shaft and movable axially into drive engagement with the drive gear. Clutch engaging elements are provided on opposite portions of the drive gears and the clutch member. Shift means utilizing a positive acting cam means positively move the clutch member into and out of engagement with the drive gears. The shift means also include a releasable latch means to positively maintain the shift means in the engaged position and a preloading means between the shift means and the clutch member to snap the clutch member into engagement.
U.S. Pat. No. 5,006,084, which issued to Handa on Apr. 9, 1991, describes a shift device for marine propulsion. A marine propulsion forward, neutral, reverse transmission incorporating a single spring for yieldably cushioning the shifting into either forward or reverse is described. Various embodiments of detent mechanisms and spring locations are illustrated as is an arrangement for providing a different spring loading in one direction from the opposite direction.
U.S. Pat. No. 6,659,911, which issued to Suzuki et al. on Dec. 9, 2003, describes a shift assist system for an outboard motor. The system regulates the torque of the engine to ensure proper effortless shifting. The system recognizes open circuit or short circuit faults and nevertheless enables the torque of the engine to be reduced to facilitate easy gear selection.
U.S. Pat. No. 6,884,131, which issued to Katayama et al. on Apr. 26, 2005, describes a shift mechanism for a marine propulsion unit. An outboard motor incorporates a driveshaft and a propulsion shaft driven by the driveshaft. The driveshaft carries a pinion. The propulsion shaft carries forward and reverse gears. The pinion always meshes with the forward and reverse gear and drives the forward and reverse gears in opposite directions relative to each other. A hydraulic forward clutch mechanism couples the forward gear with a propulsion shaft. A hydraulic reverse clutch mechanism couples the reverse gear with the propulsion shaft. A shift actuator selectively operates the forward clutch mechanism or the reverse clutch mechanism to provide forward, reverse and/or neutral running conditions for the outboard motor.
U.S. Pat. No. 6,893,305, which issued to Natsume et al. on May 17, 2005, describes a shift mechanism for a marine propulsion unit. The unit has a driveshaft and propulsion shaft driven by the driveshaft and driving a propeller. The driveshaft carries a pinion. The propulsion shaft carries forward and reverse gears. The pinion meshes with the forward and reverse gears. The pinion drives the forward and reverse gears in opposite directions relative to each other. A sleeve is rotatable with the propulsion shaft. The sleeve is slidably disposed between the forward and reverse gears on the propulsion shaft. The forward and reverse gears have teeth on a surface thereof that opposes the sleeve. The sleeve has recesses on each surface thereof that opposes the forward or reverse gear. Each tooth can enter a corresponding recess. The tooth has a length substantially the same as a length of the recess in a circumferential direction.
U.S. Pat. No. 6,942,530, which issued to Hall et al. on Sep. 13, 2005, discloses an engine control strategy for a marine propulsion system for improving shifting. An engine control strategy selects a desired idle speed for use during a shift event based on both speed and engine temperature. In order to change the engine operating speed to the desired idle speed during the shift event, ignition timing is altered and the status of an idle air control valve is changed. Theses changes to the ignition timing and idle air control valve are made in order to achieve the desired engine idle speed during the shift event. The idle speed during the shift event is selected so that the impact shock and resulting noise of the shift event can be decreased without causing the engine to stall.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.